The following description relates to depositing fluid onto a medium. An ink jet printer typically includes an ink path from an ink supply to an ink nozzle assembly that includes nozzles from which ink drops are ejected. Ink drop ejection can be controlled by pressurizing ink in the ink path with an actuator, for example, a piezoelectric transducer, a thermal bubble jet generator, or an electrostatically deflected element. A typical printhead module has a line or an array of nozzles with a corresponding array of ink paths and associated actuators, and drop ejection from each nozzle can be independently controlled. In a so-called “drop-on-demand” printhead module, each actuator is fired to selectively eject a drop at a specific location on a medium. The printhead module and the medium can be moving relative one another during a printing operation.
In one example, a printhead module can include a substrate and an actuator. The substrate can include a flow path body, which can be made of silicon and can include microfabricated flow paths and pumping chambers. The substrate can also include a nozzle layer secured to the flow path body, and nozzle layer can include nozzles formed therein. The actuator can include a layer of piezoelectric material that changes geometry, or flexes, in response to an applied voltage. Flexing of the actuator pressurizes ink in a pumping chamber located along the ink path.
Printing accuracy can be influenced by a number of factors. Precisely positioning the nozzles relative to the medium can be necessary for precision printing. If multiple printhead modules are used to print contemporaneously, then precise alignment of the nozzles included in the printhead modules relative to one another also can be critical for precision printing.